Android: Clear the clipboard when getting a null mimedata

From API 28 it is possible to clear the clipboard so we should ensure
that this is done if API 28 or later is being used. Otherwise it is not
removed, but that is due to limitations on the Android side.

Pick-to: 5.15
Change-Id: I1fe504d0e566c6923b39b2adf4540619c6b1daf7
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>

src/android/jar/src/org/qtproject/qt5/android/QtNative.java

@@ -847,6 +847,8 @@ public class QtNative
 
     private static void clearClipData()
     {
+        if (Build.VERSION.SDK_INT >= 28 && m_clipboardManager != null && m_usePrimaryClip)
+            m_clipboardManager.clearPrimaryClip();
         m_usePrimaryClip = false;
     }
     private static void setClipboardText(String text)

src/plugins/platforms/android/androidjniclipboard.cpp

@@ -63,9 +63,13 @@ namespace QtAndroidClipboard
             return;
         }
     }
-    void setClipboardMimeData(QMimeData *data)
+    void clearClipboardData()
     {
         QJNIObjectPrivate::callStaticMethod<void>(applicationClass(), "clearClipData");
+    }
+    void setClipboardMimeData(QMimeData *data)
+    {
+        clearClipboardData();
         if (data->hasText()) {
             QJNIObjectPrivate::callStaticMethod<void>(applicationClass(),
                                                       "setClipboardText", "(Ljava/lang/String;)V",

src/plugins/platforms/android/androidjniclipboard.h

@@ -53,6 +53,7 @@ namespace QtAndroidClipboard
     void setClipboardManager(QAndroidPlatformClipboard *manager);
     void setClipboardMimeData(QMimeData *data);
     QMimeData *getClipboardMimeData();
+    void clearClipboardData();
     void onClipboardDataChanged(JNIEnv */*env*/, jobject /*thiz*/);
     // Clipboard support
 }

src/plugins/platforms/android/qandroidplatformclipboard.cpp

@@ -66,6 +66,10 @@ QMimeData *QAndroidPlatformClipboard::mimeData(QClipboard::Mode mode)
 
 void QAndroidPlatformClipboard::setMimeData(QMimeData *data, QClipboard::Mode mode)
 {
+    if (!data) {
+        QtAndroidClipboard::clearClipboardData();
+        return;
+    }
     if (data && supportsMode(mode))
         QtAndroidClipboard::setClipboardMimeData(data);
     if (data != 0)